Conditioning of freshly quarried clay



June 29, 1937. s. c. I QQNS, 2,085,537

ONDITIONING OF-F`RESHLY QUARRIED CLAY Filed Jan. 1s, 1935 Patented June 29,r 1931 UNITED STAT Es PATENT OFFICE CONDITIONING F FRESHL'I URRIED Sanford c. Lyons, Bennington vt., mmm to Bird Machine Co., Walpole, Mass.,-a corpora-- tion of Massachusetts Application January 1 8, 1935, Serial No. 2,369

' (ci. zas-els) vention-may afrordsubstantial continuity of op- 13 Claims.

This invention relates to the conditioning of `freshly quarried clays, such as the `kaolins and china upts.

y5 l In conditioning clay for the market, the p ractice'usually employed devolves about slow operations carried out largely on a batch scale in expensive equipment that is spread over much space f and requires considerable labor'. 'Ihus, according to the practice generally in vogue, the freshly quarried clay is mixed with water to form a very dilut suspension, usually Aof about 1% or so solids'content, from which coarse impurities are settled out'in a'sluicing system so extensive as l5 to necessitate out-door installation with the climatic andother inconveniences incident thereto. T he suspension is then concentrated in large tanks preparatory'to-'being delivered to illter presses,which dewater. the clay to the plastic consistpncy desired for drying. The c'akes o! clay as .recovered from the lter presses 'do not -lend themselves to convenient or economical handling and/or drying. This can be seen from the fact that after a. press has taken on its capacity or load of filtered clay, operator must remove thecakes therefrom' and t ere-is a long period when illter-pr'essed'clay is unavailable fordrying from a particular press. In other words, thejelement of manual laborfcoupled with the idle period in. 30 cident to the 'operation of aillter press make for ...incompatibility with -a continuously runningdryer. E,

In accordance with the present invention, reshly quarried .clay is suspended in water to I produce a readily fiowable suspension but one ofcomparatively high solids content, namely, a

solids content of at least about 15%. Thesus pensin is then delivered as a progressively owing stream through a continuous flow centrifuge `i0 'which is ,operated 'under such conditions .as to rid it progressively and `practically completely ofcoarse Vimpurities and then through a continuous ilow electrophoretic centrifuge which combines electrophoretic and centrifugal actions to sepa- I 45 rate progressively from the stream its ne solids content and to deliver suchsolids content asa about %-solids content that can be readily and progressively dried to completion. Such. plastic 50 clay mass is preferably extruded-progressively into elongatedy bodies of small and' substantially uniform cross-sectional area that lend themselves to progressive drying to substantial completion rapidly and substantially uniformly. It is thus seen thatthe practice of the present lnclays, to produce puried marketable prodprogressively moving plastic clay mass of at least eration, beginning with a suspension of freshly quarried clay and ending with a purified and driedproductready for the market. Such practice is advantageous in that it can be performed 5;

with. compact apparatus having comparatively high capacity and yieldinga given amount of' ilnished clay product of controllable and reproy ducible quality at lower cost than a clay product produced as heretofore.

On the accompanying drawing, 1' have illusti-ated diagrammatically and conventionally apparatus such as-I employ in practicing the process of the present invention.

As illustrated on the drawing, freshly quarried 1 5.

cl y is =rst admixed with water to form a sub- ;s ntially homogeneous and iluid suspension of moderately high solids content, preferably a suspension of about 20% to 35% solids content. In

some instances, it may be`de'sirable to add tothe 20 water used asthe suspension vehicle a small amount of al dispersing agent, such `as sodium v silicate, for the purpose of deilo'cculating such ag.

gregates ot intrinsically ilne clay particles as may diameter end o the shell as suspension is being emitted throug itslarge diameter end. The suspension is fed into thecentrifuge preferably adjacent to its s mall diameter end, thereby causing 40 l the suspension to traverse substantially the full length oi' the centrifuge andthus be acted upon by centrifugalrforce'for Vthemaximum period of time commensurate' with the particular volumetric ilow of suspension being' maintained 45 through the centrifuge. The conditions of oper.-

ation' of the centrifugehincluding itsefIectiv' diameter, itsrate of rotation, and. the rate otV ilow otsspension therethrough, are such 'as vto y conduce essentially only Vto the deposition oi 50 coarseor oversized solids, suche-s sand. quartz, mica, and other grit, on the in ternaLwall of the centrifuge. Such coarse solids or impurities arereceived from the small diameter end of the cenin an annular .trough l2 and v are dis- 5y.

' 79/ 2,032,624, dated Maren 3. 1936. according to which 2 charged throughV a pipe Il. The substantialiy grit-free-` suspension is received from .the large diameter end of' the centrifuge in an annular trough I4 and may, if desired, be delivered therefrom through a pipe I5 through a rotary or otherI suitable screen I6 whichserves to eliminate from the suspension suchA fibrous material as bark,

wood, or other floating trash.

'I'he purified or refined clay suspension may then be delivered by a pipe I1 to a continuousiiow electrophoretic centrifuge Il more particularly of the type illustrated and described in detail in my patent application Serial No. 744,759, filed September 20, 1934, now Patent No. 2,057,156, datedv October 13, 1936. Such a centrifuge I9 includes, as shown, a frustro-conical shell and a propelling screw Il which functions to discharge solids depositing on the electrically charged internal wall of the shell through the small diameter end of the shell while liquid is flowing out through its large diameter end, thereby avoiding substan- -tial impairment of the electro-attractive force exercised bythe wall and hence ensuring a progressive separation of solids at substantially uniform effectiveness from the suspension, as pointed out in my last-named application. The centrii fuge I9 is subject to an electrophoretic circuit,

its shell being impressed with a positive electrical charge and being electro-insulated from its propelling screw I 9, which is impressed with the electro-negative charge. By ensuring the proper conditions of operation of the centrifuge Il, including the impression thereupon` of adequate voltage, it is possible, as pointed out in my lastnamed application, to realize the deposition of a comparatively thick paste or` plastic mass of a solids contento! as high-as about 60% to 70% -on the internal wall of the centrifuge and so to deplete the suspension of clay solids that the aqueous eilluent from the centrifuge is of comparatively very low solids content. The plastic clay mass being progressively discharged from the small diameter end of the centrifuge may be received in an annulartrough 2l at a soiids'con'- tent preferably of about 60% tol '10% `i'or further treatment presently to'be described. The aqueous eiliuent being progressivelye'mitted from' the large diameter end of the vcentrifuge may be recovered in an annular trough 2| and, as shown, be used as the aqueous medium for the preparation of other raw aqueous clay suspension, therej by conserving such residual clay asmay be present in the eiliuent.

The plastic clay mass may be progressively taken'from the trough Il through a positive-feed slul or conduit 2! to an extruding machine 2,3,

w discharges such mass through a multiplicity of apertures 24 as elongated bodies 25 of small,

' substantially uniform cross-sectional area.' 'Ihese bodies may be dried in any suitable way but, as shown, they are preferablyM transferred Vdirectly from the extruding machine to a continuous dryer o 20, comprising an endless carrier or conveyor 21. on which latter the bodies are received and onA which their drying is progressively4 effected by currents of hot air suitably brought to play thereupon. More specifically, I prefer to accomplish theextrusion and drying of the clay in the manner disclosed in my patent application Serial No. 755,191, filed November 28, 1934, now Patent No.

' application, provision' is made to keep the extruding machine from being fouled by the clay mass as well as to dry the extruded bodies progres- Ysively as they are being delivered by the extruding machine. The dried clay bodiesmay be shipped as such vto the consumer, although, in some cases, it is preferable to deliver them directly from the dryer into'a suitable crushing 'or pulverizing machine, for instance, into a hammermill, which reduces them to a pulverulent condition.

If desired, other steps may be introduced into or form part of the process of the present invention hereinbefore described. Thus, before the aqueous suspension of raw clay is introduced into the centrifuge I0, it may be permitted to remain quiescent for ashort period of time in a settling tank wherein the very coarsest of impurities, such as tend to subside promptly from the suspension,-

are permitted to settle. lThe supernatent suspension containing the more diiiicultly removable impurities, including those that can be removed only after a long period -of settling, may Athen be delivered to the centrifuge Il. When the suspension contains coloring impurities, particularly fer` ric'oxide or other coloring ferruginous compounds,

itmay be treated with a-suitable decolorlzing ,"r

chemical, such as sulphurousacid, sodium bisulphite, hyposulphurous acid,- sodiumA hyposulphite, or the like', which serves to transform such coloring compounds to colorless, water-soluble condition.

In practice, the chemical decolorizing treatment of the clay suspension is preferably followed by one or more other treatments for preventingthe colorizig chemical may be performed either before or after coarse impurities have been centrifugally removed from thesuspension.v By virtue ofl the high concentration of solids in the suspension, a comparatively small amount of decolorizing chemical is all that is necessary to create in thev suspension ample concentration of such chemical for accomplishing the desired re action on the coloring compounds.

'.lhere are some clays which contain a substantial fraction of useful intermediate-sized` clay F `.solids as well asextremely fine or colloidal clay solids. As already indicated, the action -of the centrifuge III on the stream of freshly quarried clay suspension is to remove therefrom substan- V tially 'only oversized impurities, that is, such gritty impurities as sand, quartz, mica, etc. In other words, extremely little, if any, clay lsolids are lost through the centrifugal purification effected in the centrifuge III. However, after the clay suspension has undergone the action of the centrifuge III, it may, in some instances, be advantageously subjected to a more intensive centrifugating action in asecond centrifuge constructed essentially like the centrifuge III, but operated under a set of conditions designed to remove progressively from the continuously flowing suspension the intermediate-sized clay solids, leaving in the eilluent suspension substantially only the fine or colloidal clay solids thatA can be separated from the suspension to good advantage by the com- 8,155587 bined electrophoretic and centrifugal actions of the centrifuge I8,- as hereinbeforedescribed. Such an intermediate centrifuge 30 is shown in the drawing as being capable of receiving from a feed pipe 3| entering through its small diameter endl the clay suspension previously rid .of coarse 'or oversized solids in the centrifuge I0. The intermediate-sized clay solids fraction deposted on the wall of the centrifuge 30 may be discharged vby a propelling screw 32 through the ysmall diameter endof such centrifuge and the liquid eiiiuent containing the ilne and colloidal clay in suspension therein may be vemitted through the large diameter end of such centrifuge and delivered by a pipe 33 tothe pipe I1 feeding into the continuous-how electrophoretic centrifuge I8 wherein the deposition of the i'lne and colloidal clay solids takes place. 'I 'he intermediate-sized clay solids are recovered as a plastic mas's which may be substantially. completely dried or otherwise treated in much vthe same way as is the recovered ne andcolloidal clay solids.'

. the practice which comprises suspending the clay lso Iclaimz-f; 1. In the conditioning ofY freshly quarried to produce.a purified and marketable oduct,

in Water to produce a readily flowablesuspension, progressively Vstreaming the suspension through a` centrifuge to deposit progressively underv centrifugal force on its wall oversized impurities, then progressively streaming the sus--v pension through another centrifuge, whose wallV is electrically charged to attract the ne solids` content of said suspension, toldepositfprogressively'on its wall under 4combined electrophoretic `4 and 'centrifugal forces said ne solids. content as a plastic mass while substantially constantly removing said plastic mass. from said wall to maintain substantially constant the combined electrophoretic and centrifugal forces acting to deposit said fine solids and thereby substantially constantly to maintain of substantially uniform average particle size said fine solids being deposited and removed as-a plastic mass, and drying such removed plastic mass.

2; 1n the conditioning .or freshly quarried clay to produce a puried and marketable'- product, the practice which comprises suspending the clay in waterto produce a readily'ilowable suspen-` sion, 'progressively streaming the suspension through a centrifuge to deposit progressively under centrifugal force on its walll oversized im- 1 purities. then progressively streaming the suspension through-another centrifuge, whose wall is electrically charged to attract the hue solids con- V tent of said suspension, to'. deposit progressively on' its wall under combined electrophoretic and centrifugalforces said fine`solids content as a;

to produce a purified and marketable product.,

i plastic mass while substantially-constantly removing said plasticmass from said wall to maintain substantially constant the combined electrophoretic and 'centrifugal forces acting to deposit said fine solids and thereby. substantially con-' stantly to maintain of substantially uniform average particle size saiddinesolids being vdeposited and removed as a plastic mass, progressively ex-l truding such plastic mass into elongated bodies t o'f small cross-sectional area, and drying suchbodies substantially Vuniformly to completion; 3. `In the conditioning of freshly quarried'clay the practice which comprises suspending the clay in water to produce w readily owable suspension of a solids `content' of atleast about ,15%, progressively 'the suspension through clay a centrifugeto' deposit progressively under centrifugal force on its wall oversized impurities, then progressively streaming the suspension through anotherV centrifuge. whose wall is electrically charged to attract the ne solids content of said suspension, to deposit vprogressively on its wall under combined electrophoretic and centrifugal forces said ne solids content as a plastic mass of lat least about 50% solids content while substantially constantly removing 'said plastic massfrom said wall to maintain substantially constant the combined electrophoretic and centrifugal'iorces acting to deposit said ne solids and thereby substantially constantlyto maintain' of substantially uniform average .particle size said fine Vsolids being deposited and removed as a 4plastic mass, and drying` such removed plastic Y mass.

4. In theconditioning of freshly quarried clay to produce apuried andA marketable product,

the practice which comprises suspending the clay in water to produce a readily flowable suspension of a solids content of at least about 15%, progressively streaming the suspension through a centrifuge to deposit progressively gunder centrifugal force 'on'its wall oversized impurities, then progressively streaming the suspension through another centrifuge, whose wall is electrically charged to attract the fine solids content of said suspension, to deposit progressively on its wall under combined electrophoretic and centrifugal forces said fine solids content as a plastic mass of at least about 50% solids content while sub- `stantially constantly removing saidplastic mass from said wallto maintain substantially constant to produce a purified and marketable product,v

those steps which comprise progressively streaming an aqueous suspension of such clay through a centrifuge to deposit progressively under centrifugal force onits wall oversized impurities,

and then progressively streamingthe suspension ding such plasticmass through another centrifuge, whose wall is electrically charged to attractthe fine solids content of said suspension, to deposit -progressively on its Wall under combined electrophoretic` and vcentrifugal forces said -ne solids content as a plastic' mass while substantially constantly removing said plastic 'mass from said wall to maintain substantially constant the combined electrophoretic and centrifugal forces acting to deposit said `iine solids 'and thereby substantially constantlytomaintain -of substantially uniform average particle size saidne solids -being deposited plastic `6. In the conditioning of freshly vquarried clay and 4removed as a l to -produce e puried and marketable product,

those steps which comprise suspending the clay in water to' produce Ya ilowable suspension o f at least about 15% solids content and progressively streaming the suspension through a `centrifuge to deposit progressively under 'centrifugal force on its wall oversized impurities and then progressivelystreamingthe suspension through another centrifuge, whose wallI is electrically charged to attract the fine solids. content of said suspen sion, to deposit progressively on its wall under combined uelectrophoretic and` centrifugal forces said ilne slids contentes a plasticmass of at least about 50% solids content while substantially stantially constantly to maintain of substantially uniform average particle size said fine solids being deposited and removed as a plastic mass.A

'1. In the conditioning of freshly quarried clay to produce a purihed and marketable product, those steps which comprise suspending the clay in water to produce a readily flowable suspension, progressively streaming the suspension through a centrifuge to deposit progressively vunder centrifugalforce on its wall oversized impurities, then progressively streaming the suspension through another centrifuge to deposit progressively on its wall under more intensive centrifugal force intermediate-sized clay solids vas .a plastic mass while substantially constantly removing said plastic mass from said wall to maintain substantially constant the centrifugal force acting to deposit said intermediate-sized .clay solids and thereby substantially constantly to maintain of substantially uniform average particle size said clay solids being deposited and removed as a plastic mass, and then progressively streaming` the suspension through still another centrifuge, whose wall is electrically charged to attract the fine and colloidal clay solids content of said suspension, to deposit progressively on its wall under combined electrophoretic and centrifugal forces said fine and colloidal solids content as a plastic mass while substantially constantly removing said plastic mass from said wall to maintain substantially constant the combined electrophoretic and centrifugal forces acting to deposit said fine and colloidal solids and thereby substantially constantly to maintain of substantially uniform average particle size said ne and colloidal solids being deposited and removed as a plastic mass.

8. In the conditioning of freshly quarried clay to produce a purinedand marketable product,Y

that practice which comprises suspending the clay in water in the presence of a dispersing agent to produce a readily nowable sumenslon of at least about 15% solids content, progressively streaming the suspension through ai centrifuge to deposit progressively under centrifugal force onits wall Y oversized impurities. then progressively streaming the suspension through another centrifuge, whose wall is electrically charged to attract the fine solids content of said suspension, to deposit progressively on its wall under combined electrophoretic and-centrifug`al forces said ne solids content as a plastic mass while substantially constantly removing said plastic mass from said wall to produce a purified and marketable product,

the practice which comprises suspending the clay in.an aqueous vehicle to produce a readily flowable suspension. progressively streaming the suspension through a centrifuge to deposit progressively under centrifugal force on its wall oversized impurities, then progressively streaming the suspension through another centrifuge, whose wall is electrically charged to attract the fine solids content of said suspension, to deposit progressively on its wall under combined electrophoretic and centrifugal forces said ne solids content as a plastic '.nass while causing aqueous eiiluent to be emitted from said second-named centrifuge and while substantially constantly removing said plastic mass from said wall to maintain substantially constant the combined electro-i phoretic and centrifugal forces acting to deposit said fine solids and thereby substantially constantly to maintain of substantially uniform average particle size' said fine solids being deposited and removed as a plastic mass, and 'reusing aqueous eiiluent emitted from said second-named centrifuge as aqueous vehicle for suspending freshly quarried clay in performing the first-named step of said practice.

10. In the conditioning of freshly quarried clay to produce a purified and marketable product, the practice which comprises' suspending the clay in an aqueous vehicle in the presence of a dispersing agent to produce a readily ilcwable suspension of at least'about 15% solids content, progressively streaming the suspension through a centrifuge to deposit progressively under centrifugal force on its wall oversized impurities, then progressively streaming the suspension through another centrifuge, whose wall is electricallyfcharged to attract the fine solids content of said suspension, to deposit progressively on its wall under combined electrophoretic and centrifugal forces said ine solids content as a plastic mass while causing aqueous eilluent to be emitted from said second-named centrifuge and while substantially constantly removing said plastic mass from said Wall to maintain substantially constant the combined electrophoretic and centrifugal forces acting to deposit said fine solids and thereby substantially con- Astantly to maintain of substantially uniform average particle size said fine solids being deposited and removed as a plastic mass, and reusing aqueous eilluent emitted from said secondnamed centrifuge as aqueous vehicle for suspending freshly quarried clay in performing the first-named step of said practice.

' 11. 'In the conditioning of freshly quarried clay Vto. produce a purified and marketable product,

those steps which comprise suspending the clay in water in the presence of a dispersing agent to produce a readily fiowable suspension of at least about'15% solids content, progressively streaming the suspension through a centrifuge to deposit progressively under centrifugal force on its wall oversized impurities,` then progressively streaming the suspension through another centrifuge to deposit `progressively on its Wall under more intensive centrifugal force intermediatesized clay solids as a plastic mass while substantially oonstantlyremoving said plastic mass from said wall to maintain substantially constant the centrifugal force acting to deposit said intermediate-sized clay solids and thereby substantially constantly to maintain of substantially uniform average particle size said clay solids being deposited and removed as a plastic mass, and then progressively streaming the suspension through still another centrifuge, whose wall is electrically charged to attract the fine and colloidal clay solids content of said suspension, to deposit progressively on its Wall under combined electrophoretic and centrifugal forces said fine and colloidal solids content as a plastic mass ate-sized clay solids and thereby substantially while substantially constantly Aremoving said plastic mass from said wall to maintain substantially constant the combined electrophoretic and centrifugal forces acting to deposit said ne and collodial solids and thereby substantially constantly to maintain of substantially uniform average particle size said fine and colloidal solids t being deposited and removed as a plastic mass.

12. In the conditioning of freshly quarried clay to produce a 'purified and marketable product, those steps which comprise suspending the 'clay in' an aqueous vehicle to produce a readily flow- .'able suspension, progressively streaming the sus-v pension through a centrifuge to deposit progressively under centrifugal force on its wall oversized impurities, then progressively streaming the suspension through another centrifuge to deposit progressively on its wall under more intensive centrifugal force intermediate-sized clay solids 'as a plastic mass while substantially constantly removing said plastic mass from said wall to maintain substantially constant the centrifugal force acting to deposit said intermediconstantly to maintain ofsubstantially uniform average particle size said clay solids being deposited and removed as a plastic mass, then progressively streaming the suspension through. still another centrifuge. whose wall is electrically charged to attract the ne and colloidal clay solids content of said suspension, to .deposit progressively on its wall under combined electro phoretic and centrifugal forces said ne and colloidal solids content as a plastic mass while causing aqueous eiiiuent to be emitted from said last-named centrifuge andI while substantially constantly removing said plastic mass from said wall to maintain, substantially constant the combined electrophoretic and centrifugal forces acting to deposit said fine and colloidal solids and thereby substantially constantly to maintain of substantially uniform average particle size said ne and-colloidal solids being deposited and removed as a plastic mass', andv reusing aqueous eiiluent emitted'from'said last-named centrifuge Y as aqueous vehicle for suspending freshly quarried clay in performing the first-named step.

13. In the conditioning of freshly quarried clay to produce a purified and marketable product, those steps which comprise suspending the clay in an 'aqueous vehicle in the presence of a. dislpersing agent to produce a readily fiowable sus'- pension of at least about 15% solids content, progressively streaming the suspension through a centrifuge to deposit progressively under centrifugal forcel on its wall oversized impurities,

then progressively streamingthe suspension streaming the suspension through still another A centrifuge, whose wall is electrically charged to attract the fine and colloidal clay solids content of said suspension, to deposit progressively on its wall under combined electrophoretic and centrifugal forces said fine and colloidal solids content `as a plastic mass while causing aqueous eiiluent to be emitted from said last-named centrifuge and while substantially constantly removing said plastic mass from said wall ,to maintainsubstantially constant the combined electrophoretic and centrifugal forces acting to de posit said fine and colloidal solids and thereby substantially constantly to maintain of substantially uniform average particle size said fine and colloidal solids being `deposited and removed as a plastic` mass, and reusing aqueous eilluent emitted from said last-named centrifuge as aqueous vehicle for suspending freshly quarried clay in performing the mst-named step.

SANFORD C. LYONS. 

